Once the development environment is running, you can visit
http://localhost:9991/ in your browser. By default, the development
server homepage just shows a list of the users that exist on the
server and you can login as any of them by just clicking on a user.
This setup saves time for the common case where you want to test
something other than the login process; to test the login process
you’ll want to change AUTHENTICATION_BACKENDS in the not-PRODUCTION
case of zproject/settings.py from zproject.backends.DevAuthBackend
to use the auth method(s) you’d like to test.

While developing, it’s helpful to watch the run-dev.py console
output, which will show any errors your Zulip development server
encounters.

To manually query the Postgres database, run psqlzulip for an
interactive console.

When you make a change, here’s a guide for what you need to do in
order to see your change take effect in Development:

If you change JavaScript, CSS, or Jinja2 backend templates (under
templates/), you’ll just need to reload the browser window to see
changes take effect. The Handlebars frontend HTML templates
(static/templates) are automatically recompiled by the
tools/compile-handlebars-templates job, which runs as part of
tools/run-dev.py.

If you change Python code used by the main Django/Tornado server
processes, these services are run on top of Django’s manage.py
runserver which will automatically restart the
Zulip Django and Tornado servers whenever you save changes to Python
code. You can watch this happen in the run-dev.py console to make
sure the backend has reloaded.

The Python queue workers will also automatically restart when you
save changes. However, you may need to ctrl-C and then restart
run-dev.py manually if a queue worker has crashed.

If you change the database schema, you’ll need to use the standard
Django migrations process to create and then run your migrations; see
the new feature tutorial for an example.
Additionally you should check out the detailed testing
docs for how to run the tests properly after doing a
migration.

(In production, everything runs under supervisord and thus will
restart if it crashes, and upgrade-zulip will take care of running
migrations and then cleanly restaring the server for you).